This invention relates to a heat-sensitive record material and particularly to a heat-sensitive record material which is superior in adaptibility for a high-speed recording and retainability of the developed color images, and further in which the whiteness of the unrecorded portion is stably maintained without undesired coloration and a blue-black or black-blue color superior in stably keeping the recorded images can be developed.
There has been well known heat-sensitive record materials which utilize colorforming reaction between a colorless or pale colored basic chromogenic material and an organic or inorganic color developer, in which the two colorforming materials are thermally brought into contact with each other to produce color images.
Recently, a considerable progress has been made in the field of heat-sensitive recording systems, and hat-sensitive facsimiles, heat-sensitive printers and the like become possible to make the recording speed very higher. In heat-sensitive facsimiles a recording speed of 20 seconds for a sheet of A4 size can be achieved and in heat-sensitive printers a recording speed of 120 letters per second or more can be achieved. With the improvement of hardware fields as described above, it is required for the available heat-sensitive record material to be superior in adaptability for a high-speed recording.
On the other hand, the fields applicable of these heat-sensitive record materials become wider to accompany the rapid spread of heatsensitive facsimiles, heat-sensitive printers and the like. Further, it is required for the recorded images to have various colors. For example, there are increased the cases in which a heat-sensitive record material developing a blue-black or black-blue color is required.
For these requirements, plural basic chromogenic materials each of which develops a different color are mixed to use. However, thus obtained heat-sensitive record materials have some defects, for example, that unnecessary coloration (fogging phenomenon) in the unrecorded white portion easily occurs when they are stored in the condition of a high temperature or high humidity. An improvement of the defects is strongly required.
The object of this invention is to provide a heat-sensitive record material in which the unrecorded white portion can be maintained without undesired coloration when it is stored in the condition of a high temperature or a high humidity for a long time and a stable blue-black or black-blue images can be recorded.